In such a gas burner type, in which usually at least part of said diffusion chamber is made in one piece named “burner head”, the use of a cross-lighting duct is known, to allow the flame passage from one to the other of the two flame spreaders and then to avoid the use of more spark plugs for sparking the flame ignition at such two flame spreaders. This duct is disposed transversally inside said first diffusion chamber, passing through it completely, so that to define a first and a second region inside the diffusion chamber.
These gas burners of the known art are not free of drawbacks. As a matter of fact, because of the presence of the afore said cross-lighting duct, separating the diffusion chamber—as mentioned—in two regions fluidically distinct one from another, the diffusion of the primary air/gas mixture inside said diffusion chamber is less uniform, thereby involving problems for the flame maintaining stably and homogeneously at the flame spreaders fed by the diffusion chamber, with subsequent combustion problems for the burner itself.
To improve and make the diffusion of the primary air/gas mixture more uniform inside the diffusion chamber the existence of a burner is known, whose cross-lighting duct has an upper wall disposed lower than the upper dome, usually defined by a removable lid, of the diffusion chamber and such to allow the mixture to communicate in the whole volume of the diffusion chamber, that is also between the first and the second region inside said diffusion chamber.
For example the International Application PCT/IB2011/002629 in the name of the Applicant, and still in obligation of secrecy, describes a solution identical to what afore mentioned.
This solution, although doubtless able to improve the diffusion of the primary air/gas mixture inside the chamber, with evident improving effects on the burner efficiency and the flame stability, nevertheless cannot always guarantee the presence of the gas and the primary and secondary air inside the cross-lighting duct in adapted stoichiometric conditions when the fuel gas type fed to the burner changes, and in particular when the gas is made of mixtures of different ingredients having different concentrations, this resulting in the flame not propagating inside the duct perfectly. Therefore an object of the present invention is to realize a burner allowing the inflow of the mixture and air into the cross-lighting duct in stoichiometric conditions such to guarantee a perfect flame propagation inside the duct.
A further object of the present invention is to realize a burner being also structurally simple and not requiring particular assembling procedures and modifications in existing burners.
Further object of the present invention is to realize a burner that, in addition to allow achieving the object afore mentioned, could be assembled with a certain adaptability according to the gas, or gas mixture, amount and type, feeding the burner and/or according to the sizes of the burner to be made.